The alleviatory effect of silicon （Si） on chromium （Cr） toxicity to rice plants was investigated using a hydroponic experiment with two Cr levels （0 and 100μmol L-1）,three Si levels （0,1.25,and 2.5 mmol L-1） ...The alleviatory effect of silicon （Si） on chromium （Cr） toxicity to rice plants was investigated using a hydroponic experiment with two Cr levels （0 and 100μmol L-1）,three Si levels （0,1.25,and 2.5 mmol L-1） and two rice genotypes,differing in grain Cr accumulation （Dan K5,high accumulation and Xiushui 113,low accumulation）.The results showed that 100μmol L-1 Cr treatment caused a marked reduction of seedling height,dry biomass,soluble protein content,and root antioxidant enzyme activity,whereas significantly increased Cr concentration and TBARS （thiobarbituric acid reactive substances） content.However,the reductions of seedling height,dry biomass,and soluble content were greatly alleviated due to Si addition to the culture solution.Compared with the plants treated with Cr alone,Si addition markedly reduced Cr uptake and translocation in rice plants.No significant differences were observed between the two Si treatments （1.25 and 2.5 mmol L-1） in shoot Cr concentration and Cr translocation factor.Under the treatment of 100μmol L-1 Cr＋2.5 mmol L-1 Si,higher root Cr concentration but lower shoot Cr concentration and Cr translocation factor were observed in Dan K5 than those in Xiushui 113,indicating that the beneficial effect of Si on inhibiting Cr translocation was more pronounced in Dan K5 than in Xiushui 113.Si addition also alleviated the reduction of antioxidative enzymes （superoxide dismutase （SOD） and ascorbate peroxidase （APX） in leaves;catalase （CAT） and APX in roots） and the increase of TBARS content in the Cr-stressed plants.Furthermore,the beneficial effects of Si on activities of antioxidative enzymes under Cr stress were genotype-dependent.The highest activities of SOD,POD （guaiacol peroxidase）,CAT,and APX in leaves occurred in the treatment of 100μmol L-1 Cr＋2.5 mmol L-1 Si for Xiushui 113 and in the treatment of 100μmol L-1 Cr＋1.25 mmol L-1 Si for Dan K5.The beneficial effect of Si on alleviating oxidative stress was much more pronounced in Dan K5 than in Xiushui 113.It may be concluded that Si alleviates Cr toxicity mainly through inhibiting the uptake and translocation of Cr and enhancing the capacity of defense against oxidative stress induced by Cr toxicity.展开更多
Tiller angle is very important for plant architecture and canopy structure in rice （Oryza sativa L.）. Physiological and ecological characteristics of three rice genotypes with different tiller angle habits were comp...Tiller angle is very important for plant architecture and canopy structure in rice （Oryza sativa L.）. Physiological and ecological characteristics of three rice genotypes with different tiller angle habits were compared in the paper. DI508, a genotype with changing tiller angle during the growth, has semi-erect tillers at early tillering stage, similar to genotype M09, and had erect tillers at late stage, similar to genotype 9308. In terms of dry biomass per plant, DI508 was consistently higher than those of M09 and 9308 throughout the growth. It was also a distinct difference of leaf area per plant that DI508 was larger than two others. From booting stage, DI508 and 9308 maintained higher photosynthetic ability of the topmost three leaves, while M09 showed rapid decline in photosynthesis during grain filling. It may be concluded that the genotype DI508 with dynamic tiller angle habit has a comprehensive advantage of fast growth and high weed competition at early stage and slow decline in photosynthesis at late stage.展开更多
基金supported by the Zhejiang Bureau of Science and Technology,China (2009C12050)
文摘The alleviatory effect of silicon （Si） on chromium （Cr） toxicity to rice plants was investigated using a hydroponic experiment with two Cr levels （0 and 100μmol L-1）,three Si levels （0,1.25,and 2.5 mmol L-1） and two rice genotypes,differing in grain Cr accumulation （Dan K5,high accumulation and Xiushui 113,low accumulation）.The results showed that 100μmol L-1 Cr treatment caused a marked reduction of seedling height,dry biomass,soluble protein content,and root antioxidant enzyme activity,whereas significantly increased Cr concentration and TBARS （thiobarbituric acid reactive substances） content.However,the reductions of seedling height,dry biomass,and soluble content were greatly alleviated due to Si addition to the culture solution.Compared with the plants treated with Cr alone,Si addition markedly reduced Cr uptake and translocation in rice plants.No significant differences were observed between the two Si treatments （1.25 and 2.5 mmol L-1） in shoot Cr concentration and Cr translocation factor.Under the treatment of 100μmol L-1 Cr＋2.5 mmol L-1 Si,higher root Cr concentration but lower shoot Cr concentration and Cr translocation factor were observed in Dan K5 than those in Xiushui 113,indicating that the beneficial effect of Si on inhibiting Cr translocation was more pronounced in Dan K5 than in Xiushui 113.Si addition also alleviated the reduction of antioxidative enzymes （superoxide dismutase （SOD） and ascorbate peroxidase （APX） in leaves;catalase （CAT） and APX in roots） and the increase of TBARS content in the Cr-stressed plants.Furthermore,the beneficial effects of Si on activities of antioxidative enzymes under Cr stress were genotype-dependent.The highest activities of SOD,POD （guaiacol peroxidase）,CAT,and APX in leaves occurred in the treatment of 100μmol L-1 Cr＋2.5 mmol L-1 Si for Xiushui 113 and in the treatment of 100μmol L-1 Cr＋1.25 mmol L-1 Si for Dan K5.The beneficial effect of Si on alleviating oxidative stress was much more pronounced in Dan K5 than in Xiushui 113.It may be concluded that Si alleviates Cr toxicity mainly through inhibiting the uptake and translocation of Cr and enhancing the capacity of defense against oxidative stress induced by Cr toxicity.
基金the National Natural Science Foundation of China (30700486)the Natural Science Foundation of Zhejiang Province,China(Y3110099)the China Spark Program(2008GA700004) for their support to this project
文摘Tiller angle is very important for plant architecture and canopy structure in rice （Oryza sativa L.）. Physiological and ecological characteristics of three rice genotypes with different tiller angle habits were compared in the paper. DI508, a genotype with changing tiller angle during the growth, has semi-erect tillers at early tillering stage, similar to genotype M09, and had erect tillers at late stage, similar to genotype 9308. In terms of dry biomass per plant, DI508 was consistently higher than those of M09 and 9308 throughout the growth. It was also a distinct difference of leaf area per plant that DI508 was larger than two others. From booting stage, DI508 and 9308 maintained higher photosynthetic ability of the topmost three leaves, while M09 showed rapid decline in photosynthesis during grain filling. It may be concluded that the genotype DI508 with dynamic tiller angle habit has a comprehensive advantage of fast growth and high weed competition at early stage and slow decline in photosynthesis at late stage.
